This relates to the field of medical devices and more particularly to endovascular devices having a stent.
In recent years treatment of aneurysms has included the use of stent grafts that are emplaced within the vascular networks, and include one or more stents affixed to graft material. The stent grafts are secured at a treatment site by endovascular insertion utilizing introducers and catheters, whereafter they are enlarged radially and remain in place by self-attachment to the vessel wall. In particular, stent grafts are known for use in treating descending thoracic and abdominal aortic aneurysms where the stent graft at one end defines a single lumen for placement within the aorta and at the other end is bifurcated to define two lumens, for extending into the branch arteries.
One example of such a stent graft is PCT Publication No. WO 98/53761 in which the stent graft includes a sleeve or tube of biocompatible graft material (such as Dacron or polytetrafluoroethylene) defining a lumen and several stents secured therealong, with the stent graft spanning the aneurysm extending along the aorta proximally from the two iliac arteries, and the reference also discloses the manner of deploying the stent graft in the patient utilizing an introducer assembly. The graft material-covered portion of the single-lumen proximal end of the stent graft bears against the wall of the aorta above the aneurysm to seal the aneurysm at a location that is distal of the entrances to the renal arteries. Thin wire struts of a proximal stent extension traverse the entrances without occluding them while securing the stent graft in position within the aorta when the stent self-expands, since no graft material is utilized along the proximal stent; an extension is affixed to one of the legs of the stent graft to extend along a respective iliac artery, and optionally extensions may be affixed to both legs. Another known stent graft is the Zenith AAA stent graft sold by Cook Incorporated, Bloomington, Ind.
Stent grafts are also known in which an inflatable balloon is positioned within the collapsed stent graft before and during placement of the stent graft in a patient using an introducer assembly; the balloon is then expanded to increase the diameters of the several stents and the graft material until the stent graft bears against the vessel wall at least at its distal and proximal ends. Such stent grafts are disclosed in U.S. Pat. Nos. 5,639,278; 5,562,728 and 5,718,724. In U.S. Pat. No. 5,330,528, a plurality of expandible chambers is disclosed, with several supply pipes extending to respective chambers for inflation thereof.
Use of such stent grafts requires that the graft not close off or occlude or obstruct entrances to other branch arteries, such as the renal arteries. Placement of the single-lumen or proximal end of the stent graft, at least the portion having graft material, must be located spaced axially from branch arteries and toward the aneurysm neck.
It is desired to provide an endovascular device that is useful for aneurysms that span the branch arteries, or that have intrarenal necks of minimal length.
In accordance with the present invention, an endovascular device includes at least one stent and at least one inflatable portion or member which is affixed to the stent, with the stent generally having no graft material thereon.
In one embodiment, the inflatable portion is disposed about a lumen of the device to define a cuff and is utilized either to expand a stent or to define a seal externally to a stent or to a stent graft, and both may be found on a particular device of the present invention. The inflatable portion may be so oriented as to be annular, or may be spiral, or may be asymmetric in its inflated state. If a device includes more than one inflatable portion, each such portion may be inflatable by a dedicated discrete lumen, or a single lumen with multiple branches to the respective inflatable portions.
In another embodiment, the device of the present invention may be used with a stent graft and extend radially outwardly therefrom to enter a branch vessel. In one particular application where the stent graft is to be emplaced for treating an abdominal aortic aneurysm, the device of the present invention would be affixable to the stent graft remote from the iliac legs thereof for placement at a proximal neck of the aneurysm, to enter one of the renal arteries and to define a lumen in communication with the stent graft lumen. The stent of the device would be expanded within the proximal portion of the renal artery. A plurality of such devices could be utilized with the stent graft for maintaining the patency of numerous branch arteries.
In another aspect, the device of the present invention could be utilized to extend from the single-lumen end of a stent graft that otherwise would terminate only just adjacent to a branch artery; the device could be used for aneurysms having proximal necks of minimal length at the renal artery entrances, where conventional stent grafts could not generally be used. The stent of the device would comprise a plurality of spaced struts or legs and would traverse the branch artery entrance without occluding it since no graft material would be utilized on the stent, allowing blood perfusion through openings between the stent struts or legs. An inflatable portion of the device would surround the end portion of the stent graft and be inflatable to become pressed against the vessel wall, thereby sealing the aneurysm.
In a further embodiment, a device of the present invention could comprise an elongate main stent either without graft material or with graft material at both the distal and proximal end portions. Additional stents could extend radially outwardly from the main stent for placement within branch vessels, each with one or more inflatable portions, and each defining a lumen in communication with the lumen of the main stent such as through openings between struts of the main stent.
Another embodiment of the stent/balloon of the present invention could include a plurality of members affixed along the outer stent surface that are spaced apart when deflated providing spacings for instrumentation to extend therebetween and outwardly from the stent, but which press against each other and the vessel wall to seal about the stent when inflated.
An additional embodiment provides an occlusion device wherein, for example, a pair of opposed inflatable portions are affixed to the inner surface of the stent such that upon inflation they press against each other and traverse the lumen of the stent.
In additional aspects, the device of the present invention could utilize stents with a pattern of spiral struts, or with a series of stent segments. A stent may be utilized that includes struts at one end that are expandable to rotate radially outwardly until in engagement with the wall of the aorta about the periphery of a branch vessel, for securing the placement of the device with respect to the branch artery.
The present invention also includes a method comprising the steps of deploying a stent and an inflatable member at a deployment site within a vessel of a patient, and inflating the inflatable member to abut the vessel wall and define a seal between the stent and the vessel wall.
Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings.